Convolute cardboard tube, apparatus and method for manufacturing the same

Abstract

A plastic film roll includes: a convolute cardboard tube including a tubular body having a tubular body wall formed by a plurality of layers of a straight rolled cardboard sheet having a weight equal to or less than 300 gsm; a plastic film wound about the convolute cardboard tube to form a plurality of plastic film windings around the convolute cardboard tube, the plastic film windings creating a radial compression force equal to or greater than 10 bar on the tubular body wall, wherein the cardboard sheet includes a plurality of fibers, at least a majority of the fibers being substantially aligned in a tangential direction relative to the tubular body to allow the convolute cardboard tube to resist the radial compression force.

The invention claimed is: 
     
       1. A method for manufacturing a convolute cardboard tube, the method comprising:
 unwinding a roll of a preselected cardboard in a machine direction tangential to the roll of the preselected cardboard by rotating the roll along a first rotation axis R1, thereby obtaining an unwound cardboard sheet, the preselected cardboard including a plurality of fibers, at least a majority of the plurality of fibers being substantially oriented in the machine direction; 
 straight rolling the unwound cardboard sheet onto a tube forming roller rotating about a second rotation axis R2 into the convolute cardboard tube, the convolute cardboard tube including at least a majority of the plurality of fibers oriented in a winding direction; and 
 cutting the unwound cardboard sheet along its width, 
 wherein the second rotation axis R2 is parallel to the first rotation axis R1; and 
 wherein straight rolling the unwound cardboard sheet includes rotating the unwound cardboard sheet along the second rotation axis at a speed of about 1 m/s to about 3 m/s. 
 
     
     
       2. The method as claimed in  claim 1 , further comprising:
 after unwinding the roll of preselected cardboard, applying adhesive to the unwound cardboard. 
 
     
     
       3. The method as claim in  claim 2 , wherein the adhesive is PVA, dextrin or silicate. 
     
     
       4. The method as claim in  claim 2 , wherein the adhesive is ultraviolet-activating adhesive or heat-activating adhesive. 
     
     
       5. The method as claimed in  claim 1 , wherein the preselected cardboard includes trimmed cardboard. 
     
     
       6. The method as claimed in  claim 1 , wherein cutting the unwound cardboard sheet along its width is performed after the straight rolling of the unwound cardboard sheet into the convolute cardboard tube to separate the convolute cardboard tube from a rest of the unwound cardboard sheet. 
     
     
       7. The method as claimed in  claim 1 , wherein the preselected cardboard has a tensile resistance equal or greater than 60 kg/mm. 
     
     
       8. The method as claimed in  claim 1 , further comprising drying the convolute cardboard tube until the tube has a humidity level of less than or equal to 7%. 
     
     
       9. The method as claimed in  claim 1 , further comprising connecting at least two convolute cardboard tubes for forming another convolute cardboard tube of a desired length. 
     
     
       10. The method as claimed in  claim 9 , wherein connecting at least two convolute cardboard tubes for forming another convolute cardboard tube of a desired length further comprises connecting the at least two convolute tubes with adhesive, with male-female joints, or by spiraling a finishing band around the connected tubes. 
     
     
       11. The method as claimed in  claim 1 , further comprising cutting the convolute cardboard tube along its length to form at least one convolute cardboard tube piece having a desired length. 
     
     
       12. The method as claimed in  claim 1 , wherein unwinding the roll of the preselected cardboard and straight rolling the unwound cardboard sheet are performed simultaneously. 
     
     
       13. The method as claimed in  claim 1 , wherein straight rolling the unwound cardboard sheet includes rotating from 6 to 10 times the tube forming roller. 
     
     
       14. The method as claimed in  claim 1 , wherein the unwound cardboard sheet is cut proximal to the tube forming roller. 
     
     
       15. The method as claimed in  claim 1 , wherein an end edge of the unwound cardboard sheet is engaged and guided along a circular path around the tube forming roller to form a first winding of the convolute cardboard tube. 
     
     
       16. The method as claimed in  claim 1 , wherein the end edge is maintained around the tube forming roller with vacuum. 
     
     
       17. The method as claimed in  claim 1 , wherein after cutting the unwound cardboard sheet along its width, the convolute cardboard tube is removed from the tube forming roller by pushing an abutting element therealong.